Surfactant-foam depressant emulsion compositions

ABSTRACT

EMULSIONS OF SILICONE-BASED FOAM DEPRESSANTS DISPERSED IN A LOW CLOUD POINT LIQUID NONIONIC SURFACTANTS AND INCORPORATED INTO ALKALINE DETERGENT COMPOSITIONS TO PROVIDE IMPROVED DETERGENT COMPOSITIONS WHICH OBVIATE THE NEED FOR THE ADDITION OF SUPPLEMENTAL FOAM DEPRESSANTS DURING CONTINUOUS WASH OPERATIONS. THE EMULSIONS OF THE PPRESENT INVENTION GENERALLY COMPRISE FROM ABOUT 10 TO 50 PERCENT BY WEIGHT OF SURFACTANT. THEY ARE STABLE OVER A PERCENT BY WEIGHT OF SURFACTANT. THEY ARE STABLE OVER A WIDE TEMPERATURE AND CONCENTRATION RANGE AND CAN EASILY BE INCORPORATED INTO SOLID ALKALINE DISHWASING AND DETERGENT COMPOSITIONS IN EFFECTIVE CONCENTRATION OF FROM 1 TO 5 PERCENT BY WEIGHT OF THE TOTAL COMPOSITIONS. THE COMPOSITIONS EMPLOYING THE EMULSION ARE USEFUL IN BOTH INDUSTRIAL AND DOMESTIC WASH OPERATIONS.

United States Patent 3,829,386 SURFACTANT-FOAM DEPRESSANT EMULSIONCOMPOSITIONS Walter F. Wegst, Grosse lle, and Otto T. Aepli, Southgate,Mich., assignors to BASF Wyandotte Corporation, Wyandotte, Mich.

No Drawing. Continuation of abandoned application Ser. No. 866,715, Oct.15, 1969. This application Oct. 16, 1972, Ser. No. 297,803

Int. Cl. Clld 3/06, 3/16 U.S. Cl. 252135 4 Claims ABSTRACT OF THEDISCLOSURE Emulsions of silicone-based foam depressants dispersed in lowcloud point liquid nonionic surfactants are incorporated into alkalinedetergent compositions to provide improved detergent compositions whichobviate the need for the addition of supplemental foam depressantsduring continuous wash operations. The emulsions of the presentinvention generally comprise from about 10 to 50 percent by weight ofdepressant and from about 50 to 90 percent by weight of surfactant. Theyare stable over a wide temperature and concentration range and caneasily be incorporated into solid alkaline dishwashing and detergentcompositions in effective concentration of from 1 to 5 percent by weightof the total compositions. The compositions employing the emulsion areuseful in both industrial and domestic wash operations.

This is a continuation of application Ser. No. 866,715, filed Oct. 15,1969, now abandoned.

The present invention relates to detergent formulations and foamdepressants therefor. More particularly, the present invention concernsemulsions of a silicone-based foam depressant dispersed in a low cloudpoint liquid nonionic surfactant and the improved detergent formulationsresulting from the use thereof.

Aqueous solutions of alkaline detergent formulations which includevarious water treating compounds are widely employed for cleaning foodhandling and processing equipment, eggs, textiles, plastics and similarsolid substrates. However, continual usage of the alkaline detergent islimited because of foams produced by the interaction between thedetergent and the soil deposits sought to be removed, such as, residuesfrom eggs, milk and other fatty or proteinaceous matter.

The foam problem is somewhat alleviated by the addition of a surfactant,usually a low cloud point nonionic surfactant, to the detergentformulation. The addition of this type of surfactant to an alkalinedetergent formulation greatly enhances the wetting and emulsification ofsoil residues sought to be removed. Furthermore, by vir tue of the factthat these surfactants are essentially insoluble at elevatedtemperatures of about 120 to 180 F., they depress or suppress the foamdeveloped by the interaction of the alkaline materials in the detergentand the soil deposits. Additionally, since these surfactants are solubleat low temperatures of about 60 to 100 F., they contribute to the readyrinsing of cleaned surfaces with cool or tepid water to providesubstrates or surfaces free of standing droplets or water breaks.

During continuous cleaning operations, however, oftentimes, thesurfactant will contribute to and develop excessive foams whichinterfere with spraying, rinsing and pumping operations thereby causingobjectionable overflows. When these objectionable conditions arise, ithas become the practice to add a supplemental foam depressant, usuallysilicone-based, to the aqueous detergent solution. This step in theoperation requires personal attention thereby resulting in man-hourexpense. Furthermore, if too much depressant is employed, then thecleaned substrates may have streaked surfaces, water breaks, standingdroplets and the like. However, this manipulative step is necessarybecause attempts to incorporate silicone-based foam depressants directlyinto a1- kaline dishwashing and detergent formulations have beenunsuccessful. Although freshly prepared silicone-containing formulationsare quite acceptable, it appears that after a few Weeks of aging, thealkaline materials react with and decompose the silicones, therebynegating their efficacy in the formulation.

It is therefore an object of the present invention to provide animproved solid alkaline detergent formulation having a foam depressantincorporated therein. It is another object of the present invention toprovide an im proved silicone-containing solid alkaline detergent formulation which is not susceptible to silicone degradation over extendedperiods of time. Still another object of the present invention is toprovide an emulsion composition consisting essentially of a foamdepressant in a low cloud point nonionic surfactant which is easily andadvantageously employed in solid alkaline detergent formulations. Itwill become apparent to those skilled in the art that these and otherobjects are achieved by the present invention from a consideration ofthe following detailed description and examples thereof.

In accordance with the present invention, it has now been found that bythe addition of an emulsion composition consisting essentially of (a) asilicone-based foam depressant and (b) a low cloud point nonionicsurfactant, the problems heretofore associated with the addition of asilicone foam depressant into an alkaline detergent are overcome. Thealkali constituent of the detergent formulation has been found not toreact with and degrade the silicone-based depressant over a considerableperiod of time. The reasons for this phenomenon are not known, but thenonionic surfactant appears to encapsulate the silicone-based depressantthereby protecting it from the alkali constituents of the formulation.By using a surfactant as the emulsifier, additional advantages accrue todetergent formulations prepared therewith. First, the surfactantdisperses the depressant in an aqueous use solution so that thedepressant is not selectively skimmed olf the solution surface andwashed away as overflow, thereby providing a long-lasting foamdepression to the solution for extended washing periods. Secondly, thesurfactant avoids production of hydrophobic surfaces, i.e., waterbreaks, standing droplets and the like, on the cleaned substrate orsurface.

The emulsions contemplated by the present invention generally compriseabout 10 to 50 percent by weight of depressant, based on the totalweight of the emulsion, and from about 50 to percent by weight ofsurfactant, based on the total weight of the emulsion. Preferably, theemulsion comprises about 10 to 40 percent by weight of depressant andfrom about 60 to 90 percent by weight of surfactant. They are preparedby dispersing the depressant in the surfactant by any conventionalmethod known in the art such as by agitation, stirring and the like.

The silicone-based foam depressants contemplated for use herein are theliquid siloxanes. These compounds, which are widely known andcommercially available, generally consist of substituted orunsubstituted polyal kylsiloxanes or alkyl polysiloxanes. Typicalexamples of these compounds include, for example, polydimethylsiloxane,dimethyl polysiloxane and the like. All of the commercially available,non-emulsified, silicone-based siloxane foam depressants can be usedwith equal efficacy in the present invention.

The nonionic surfactant dispersing agents contemplated by the presentinvention generally comprise the normally liquid oxyalkylated adducts ofhydrophobic bases. These surfactants are generally prepared bycondensing, under oxyalkylation condition, an alkylene oxide having fromabout 2 to 4 carbon atoms, such as ethylene oxide, 1,2- propylene oxide,the butylene oxides, and the like, as well as mixtures thereof, with ahydrophobic base having at least one reactive hydrogen atom. Typicalexamples of such surfactants include, for example, the ethoxylatedadducts of alkylphenols corresponding to the formula:

R-Owmmm wherein R is alkyl having from about 8 to 12 carbon atoms and nis an integer such that from about 50 to 80 percent by weight of thesurfactant consists of ethylene oxide.

Another class of useful surfactants correspond to the formula:

2 4 )-a( 3 6 )b( 2 4 )a wherein b is an integer such that the (C H O)group has a molecular weight of from about 800 to 4000 and preferablyfrom about 1500 to 2000; and a is an integer such that the finalmolecular weight of the surfactant ranges from about 2000 to 5000 andpreferably from about 2500 to 4500. These surfactants and their methodof preparation are more particularly described in US. Pat. No.2,674,619.

Still another class of suitable surfactants comprises the oxyalkylatedadducts of higher aliphatic alcohols and mixtures thereof. Thesesurfactants are prepared by condensing ethylene oxide and propyleneoxide, either sequentially or as a mixture, with said higher aliphaticalcohols. These surfactants are more particularly described in US. Pat.No. 3,340,309. In the practice of the present invention, it is preferredto employ surfactants selected from the latter two classes.

As noted previously, the emulsions, which are prepared by conventionalmethods are well known in the art, are stable over a wide range ofconcentrations as well as temperatures.

In accordance with the present invention, the present emulsions areadvantageously employed in solid alkaline detergent formulations. Thesedetergent formulations generally consist of from about 25 to 88 percentby weight of an alkali material such as anhydrous soda ash, the sodiumphosphates, metasilicates, sodium borate, and the like, as well asmixtures thereof. To prevent scaling and water precipitates caused bythe alkali in aqueous solutions, various water treating compounds areadded to the by Weight of the total formulation. Because the dispersingagent for the depressant is a surfactant, further amounts of surfactantneed not be incorporated into the formulation. The emulsion is added tothe alkali detergent composition by any conventional mode such as aribbon mixer or the like.

Optionally, a germicidal composition, such as[(monotrichloro)-tetra-monopotassium dichloro]penta-isocyanurate, ineffective concentrations of from 1 to 10 percent by weight can also beincorporated into the formulation.

It has been observed that when silicone-based depressants areincorporated into alkali formulations in accordance with the presentinvention, no silicone degradation occurs over extended periods of timeof at least 5 months.

The following examples which are not to be construed as being undulylimitative of the present invention set forth specific embodimentsthereof. In Examples I-XI specific alkali detergent formulationsadvantageously em ploying the emulsion of the present invention are setforth. In all the examples, unless otherwise indicated, all parts byweight.

EXAMPLE I An alkali detergent composition was prepared which consistedof the following ingredients:

Ingredients: Parts by weight Soda ash, anhydrous 68.00 Sodiummetasilicate, anhydrous 10.00 Sodium tripolyphosphate 20.00

Emulsion of 0.10 parts of dimethyl polysiloxane dispersed in 0.90 partsof a liquid nonionic surfactant 1 1.0 [(Monotrichloro) tetramonopotassium dichloro]penta-isocyanurate 1.00

The surfactant was prepared by condensing under oxyalkylation conditiona mixture of higher aliphatic alcohols having from 12 to 15 carbon atomswith a mixture of propylone oxide and ethylene oxide.

EXAMPLES I I-X In each of the following examples, which are set forth inTable I, a plurality of alkali detergent compositions were prepared. Ineach example the foam depressant and surfactant were introduced into thecomposition as an emulsion in accordance with the present invention. Thesurfactant employed was the same as that described in Example I. Thegermicidal ingredient was again, [(monotrichloro) tetra monopotassiumdichloro]pentaisocyanurate.

TABLE I Ingredients, in parts Emulsion composition Sodium Sodiumtripoly- Dirnethyl Soda ash nietasilicate, phosphate, poly- Nonionicanhydrous anhydrous anhydrous siloxane surfactant Getmicide alkali inweight concentrations ranging from about 10 to percent of the totalweight of the formulation. Representative of these compounds is, forexample, the alkali polyphosphates which are the most predominantlyemployed water treating compounds.

The emulsion of the present invention is employed in a typical alkalinedetergent formulation in a concentration ranging from about 1 to 5percent by weight of the total formulation, preferably from about 1 to 3percent The above formulations, in Examples II-X, set forth detergentformulations, which contain from 1% to 5% by weight of the emulsion, theemulsions consisting of from 10 to 50% by weight of depressant and from50 to by weight of surfactant. It has been found that within thesedefined ranges, a proper balance between depressant and surfactant andbetween surfactant and alkali is obtained.

5 EXAMPLE x1 An alkali detergent composition was prepared by mixingtogether the following ingredients:

Ingredient: Parts by weight Soda ash, anhydrous 67.6 Sodiummetasilicate, anhydrous 10.0

Emulsion of 0.4 part of dimethyl polysiloxane and 1.0 part of a nonionicsurfactant 1 1.4 Sodium tripolyphosphate, anhydrous 20.0 Germicide 2 1.0

1 The surfactant was the same as employed in Example I. The germicidewas the same as employed in Example I. A freshly prepared sample of thiscomposition was then tested for foam control by the procedure describedhere inafter. Fifty ml. of a 0.8% by weight aqueous solution of thecomposition was placed in a 250 ml. graduated cylinder maintained at 120F., and was manually shaken for 30 seconds. The foam produced by shakingwas then measured. Thereafter, this procedure was repeated, except thatone drop of homogenized whole egg was added to the solution. After handshaking, the foam height pro duced was observed and recorded. Thisprocedure was repeated a plurality of times for various dropwise increments of whole egg addition to the solution. The results from thesetests are tabulated below in Table II.

TABLE II No. of drops of whole egg: Foam height, in ml. 0 1 0 2 Trace 3Trace 5 5 8 12 30 The procedure outlined above was then repeated using a0.4% by weight aqueous solution of the composition. The results of thesefoam height tests using the 0.4%

Twenty-two and one-half weeks later, the same 0.8% and 0.4% aqueous usesolutions as employed above were retested for foam height production todetermine if silicone degradation had occurred. The results from thesetests are tabulated below in Table IV.

TABLE IV Number of drops 0.8% aqu ous solution, 0.4% aqueous solution,of whole egg foam height, in ml. foam height, in ml.

0 0 0 0 Trace 0 5.0 3 14. 0 5 21. 5 7 31. 0

It can be seen from a comparison of Table IV with Tables II and III,that after 22.5 weeks the silicone depressant had been subjected tolittle or no degradation, thereby evidencing the storage stability ofdetergent formulations prepared in accordance with the presentinvention.

What is claimed is:

1. A method for preventing the degradation of silicone based foamdepressant in a solid alkaline detergent composition consistingessentially of:

(a) from about 25 to 88 percent by weight of an alkali material selectedfrom the group consisting of soda ash, sodium metasilicate, sodiumphosphate, sodium borate and mixtures thereof;

(b) from about 10 to 60 percent by weight of a water treating compoundwhich is an alkali metal polyphosphate; and

(c) from about 0.1 to 2.5 percent by weight of a silicone based foamdepressant selected from the group consisting of polydimethylsiloxaneand dimethyl polysiloxane,

by the method of (l) dispersing the silicone based foam depressant ofingredient (c) above in a nonionic liquid surfactant to form an emulsionof said depressant and said surfactant, said emulsion containing fromabout 10 to 50 percent by weight of said depressant and from about 50 to90 percent by weight of said surfactant; said nonionic liquid surfactantbeing selected from the group consisting of:

(i) the ethoxylated adducts of alkylphenol corresponding to the formula:

wherein R is alkyl having from about 8 to 12 carbon atoms and n is aninteger such that the ethylene oxide constitutes from about 50 topercent by weight of the surfactant,

(ii) a surfactant corresponding to the formula:

wherein b is an integer such that the (C H O) group has a molecularweight of from about 800 to 4,000 and a is an integer such that thefinal molecular weight of the surfactant ranges from about 2,000 to5,000, and

(iii) the water-soluble cogeneric mixture of ethylene oxide andpropylene oxide adducts of higher aliphatic alcohols, and

(2) mixing with solid alkaline detergents ingredients of (a) and (b)above in such proportion that from about 1 to 5 percent by weight ofabove said solid alkaline detergent is said emulsion of (1) above.

2. The method of claim 1 wherein said emulsion contains from about 10 to40 percent by weight of said depressant and from about '60 to percent byweight of said surfactant.

3. The method of claim 2 wherein said emulsion is from about 1 to 3percent by weight of said solid alkaline detergent.

4. The method of claim 1 wherein said surfactant .of said emulsion beingfree of an aromatic component.

References Cited UNITED STATES PATENTS 3,250,727 5/1966 Noll et al.252358 3,329,625 7/1967 Hoxie 252358 3,336,231 8/1967 Marsh et al 2525453,421,940 1/1969 Wedell et al. 13429 FOREIGN PATENTS 525,433 5/1956Canada. 1,454,789 5 1966 France.

841,257 7/ 1960 Great Britain.

LEON D. ROSDOL, Primary Examiner P. E. WILLIS, Assistant Examiner US.Cl. X.R.

